A variety of devices requiring batteries such as cellular phones, wireless electronic equipment and electronic vehicles have been developed. This development of the devices has brought about an increase in demand for secondary batteries. In particular, in addition to the trend toward size reduction of electronic products, the weight and size of secondary batteries are being gradually reduced.
In response to this trend, recently, lithium metal secondary batteries (lithium metal batteries, LMB) receive much attention. A lithium metal secondary battery uses lithium for a negative electrode. Lithium has advantages of low density and low standard reduction potential of −3.04 V, thus being lightweight and imparting a high energy to secondary batteries produced therefrom.
Korean Patent Laid-open No. 2013-0043117 discloses lithium secondary batteries utilizing lithium metal oxides such as LiNiCoMnO2, LiNiO2, LiCoO2, LiMn2O4, and LiFePO4. In general, a secondary battery uses lithium oxide for a negative electrode. This is due to very excellent reactivity of lithium metal. Lithium metal reacts with moisture in the air to produce by-products such as LiOH, Li2O and Li2CO3. In addition, when a lithium metal used for an electrode is exposed to an electrolyte solution, resistance material is produced. This may significantly deteriorate performance of produced batteries and cause internal short circuit. In addition, disadvantageously, lithium is difficult to handle and be utilized as electrodes due to poor strength.
Thus, there is a need for development of electrodes that use a lithium metal to improve energy efficiency, solve the reactivity problem of lithium and simplify the production process.